358 Dr. S. J. Hickson on a neio Species 



slight acknowledgement of my indebtedness to name this 

 prawn (which turns out to be a new species of the genus 

 Atya) Atya Wyckii. 



Many species of this remarkable freshwater genus are now 

 known. Species are found in Mexico, the West Indies, the 

 Cape-Verde Islands, Java, Batjan, Bali, Celebes, the Philip- 

 pines, Tahiti, Samoa, and New Caledonia. 



In most cases they are found in rivers and brooks running 

 into the sea, frequently accompanied by freshwater species of 

 the genus Palcemon. In only one case do we find it mentioned 

 that its habitat lies much above the sea-level, namely A. sul- 

 catipes, 300 feet above the level of the sea at San Nicolao, 

 Cape- Verde Islands (6, p. 49). The species I am about to 

 describe lives in Lake Tondano, at a height of 2000 feet above 

 the sea-level. 



In many respects it is a much more slender and delicate 

 form than any of its nearly allied species, and the three pos- 

 terior pairs of walking-legs are equal in length and covered 

 with a very sparse covering of fine hairs and a very few thick 

 thorn-like hairs. 



In most of the species of Atya the most remarkable feature 

 is the mode of attachment of the chelse of the first two 

 walking-legs. The propodos is not attached at its proximal 

 extremity to the carpos, but is prolonged nearly as far behind 

 the articulation as it is in front. Moreover, the carpos has 

 usually a most extraordinary shape, being either irregularly 

 triangular or crescent-shaped, with the propodos articulating 

 with the lower angle or horn. This is not the case with A. 

 Wyckn. In the posterior chelate limb the carpos is long and 

 cylindrical, as it is in the nearly allied genus Caridina and 

 in Palamon and other typical genera of the family. In the 

 anterior chelate limb, however, the carpos is shorter and much 

 wider at the distal than at the proximal extremity. In both 

 the propodos is not prolonged behind the articulation with the 

 carpos. 



The tuft of hairs v.'hich is found at the ends of the chelge 

 in all species of Atya is also present in this one, and hidden 

 among the dense hairs of each tuft is a hook. This hook is 

 not seen at first, as it is completely hidden by the hairs ; but 

 it may readily be seen by soaking the claw in oil of cloves 

 and examining it as a transparent object with the microscope. 

 It may be that these hooks are present in other or all species 

 of Atya ; but they have never yet been figured. 



We have, unfortunately, no precise information as to the 

 size of many of the species ; but this one seems to be, if not 

 the smallest, at any rate one of the smallest known. Thus, 



